Reference · Engine

The front end

partialfrom#18#19#21

Main's chooser (0x80030158)

Main (0x800185f8) first shows the legal still, the THQ, Nickelodeon and n-Space logos, and the opening cinematic (0x80074958(-1, 0)), then runs it with mode -1. It cycles: the front end (0x8003eb28(30)), then a demo, then the opening, and back. A demo skipped with a button (the movie player 0x8008b448 returns 1; 0 when it ran to its end) goes straight back to the front end, with no opening. It returns the mode the front end picks. A demo is movie 3, 4 or 5 (DEMO01-03.STR, 0x8008b100/14c/198), chosen by rand() % 3. rand (0x8002fb7c) is x = x * 214013 + 2531011 from 0x2dcf1a5, returning bits 16-23.

The front end (0x8003eb28)

It loads MENU.TEX (file 108) to VRAM (0, 256), 576 x 256 (the rectangle at 0x800c40d8), and database 0's models, animations and hierarchies. Hierarchies 1-37 get copies, and model 1038 is the sign. 0x8001dbcc marks the six backdrop CLUT rows (688, 506-511) semi-transparent. Then the title loop (0x8003d884) runs at 30 frames a second, two vertical blanks a frame.

Each frame:

• every 30 frames (0x800c4080 % 30) a backdrop fade starts;
• the pads: Up, Down or Select move between the three items (sound 3 or 4), X picks (Start Game: the submenu 0x8003cf80; Load Game: the card menu 0x800398bc(8, 1, 0, 0); Audio: 0x80041970), Triangle leaves (-1); holding L1, R1, L2 and R2 together plays sound 5;
• the menu draw (0x80035ab8): a fade step, the backdrop, the items, the 3D camera (0x80040268), the babies (0x8003f41c), the sign;
• CANCEL and ACCEPT with their buttons (0x80035550, 0x80035674);
• a countdown from 300 x 30 loses 5 a vertical blank (0x800c3f1c). At 0, or on Triangle, the front end returns -1 and the chooser moves on. Any move resets it.

The backdrop (0x80034fdc, 0x8003528c, 0x80034e80)

Six 128 x 128 4-bit patterns in CHARACTR.RAW, three across and two down from (576, 256) (the third column on the next page). Pattern (c, r) has its CLUT at (688, 511 - (c + 3r)). Two layers, each two 256 x 256 quads (x -256..256, y -128..128, texels 0-255) through a 128 x 128 texture window on the pattern:

• A (0x8003528c): opaque, pattern 0x800c406c/70, grey 0x800c408d - 0x800c408c;
• B (0x80034fdc): added, pattern 0x800c4064/68, grey 0x800c408c.

A fade step (0x80034e80): with the level at its full value, A moves to the next pattern; the level falls 16; at 0, B moves to the next pattern and the level returns to full. Both start on pattern (2, 0) at 0x80.

The title menu's items (0x8003d5a0)

"Start Game", "Load Game", "Audio" (pointers at 0x800bb6c0, 0x800bb51c, 0x800bb694), font 1, spacing 1, centred across. They start at y 200, 250, 300 and slide at 12 a frame to 25, 50, 75, then wobble 4 times. They are drawn white, the chosen one yellow (0x05ffff), each over a black shadow 2 down and right.

The Audio menu (0x80041970)

The title runs it on X at Audio, after sound 2 and the items sliding away (0x8003de08). It takes no arguments. Checked in the oracle (probe runs, frames 884-1300).

What it edits

Three words of the game state (0x800c5678):

It copies all three at the start (sp+0x19c, 0x1a0, 0x1a4) for Triangle. The cursor (fp) is 0 Music, 1 Sfx, 2 the stereo item, and starts on Music each time. The pads (port 1 at 0x800cda18; the release test reads both ports), a game frame:

• Triangle pressed (0x800422b0): sound 1, the three copies go back, the result is 0.
• Cross or Start pressed (0x800422f8): sound 2, the result is 1.
• Up pressed (0x80042338): sound 4, the cursor goes back one, 0 to 2.
• Down or Select pressed (0x80042364): sound 3, on one, 2 to 0.
• Left or Right released (0x8001bda4(pad, 8 or 6, 1): history & 3 is 2) with the cursor on Sfx: sound 5. Each one released plays it.
• Left or Right pressed on the stereo item (0x800423f4): the flag flips. No sound.
• Left held (0x80042540) or Right held (0x800425dc), on Music or Sfx: the value goes down or up 1, clamped to 0-100. Both held: down, then up.

So a volume moves 1 a game frame while held, 2 vertical blanks. The music volume is heard at once: every frame it is held, even at a limit, it goes to the song playing (0x8006ffa8(0x800b803a, v, v), SsSeqSetVol 0x800a91a0; 0x800b803a is the menu set's song, +0x0a of 0x800b8030). The effects volume is heard when sound 5 plays on the release, since 0x8006f26c keys every effect on at 0x800c5688.

Oracle: Left held 40 vertical blanks on Music, 90 to 70 (the song volume 0x59 to 0x46 one a frame); Down, then Left held 30 on Sfx, 100 to 85, and sound 5 once on the release; Right on the stereo item, 0 to 1, again, 1 to 0. Right held on Music from 90 stops at 100; Triangle then gives sound 1 and 90 again.

Cross, Start or Triangle end the menu that frame (0x800428ac): the music volume (kept or restored) goes to the song again, the boombox's target z returns to 1000 at 50, and every model the menu made is freed (0x800219d8, 0x80042cbc), the boombox too. There is no slide out. It returns the result (sp+0x198), which the title ignores: it slides its three items in again (0x8003d5a0), Audio still chosen.

The menu does not touch the card. The values stay in the game state, which a save writes whole (in a record, +0x2c, +0x30, +0x34). 0x80070c24, called from show_still (0x80030010) while the boot stills show, tries both cards and copies the three back from the last record used (0x800702d8). The mono flag is read by the positional sounds (0x8006f4c0, 0x8006f644, 0x8006f88c): with it set they get one volume for both sides (0x8006fd68), otherwise a pan (0x8006fc40).

The positional sounds (0x8006f644(sound, position)):

• The listener is the camera (0x800de460's position, copied to 0x800e3498 each frame by 0x8006f88c) and its heading, the bearing of its forward axis (0x800c4be4).
• Out of range when |dx| or |dz| exceeds 0xfffe or |dy| reaches 0x7fff.
• Distance d = dx^2 >> 14 + dy^2 >> 12 + dz^2 >> 14 (0x800c435c = 14).
• 0x8006fd68 with the table at 0x800b8024 (near 128, far 16384, max 127): 127 under 128, 0 past 16384, else 127 - (d - 128) / 128; then no more than the effects setting (+0x10), and not below 0.
• 0x8006fc40, the angle a = the sound's bearing less the camera's: the volume loses (v * 89 >> 8) * max(0, -rcos a) / 4096 (up to about a third from behind); then the side away from the sound loses (v * 192 >> 8) * |rsin a| / 4096 (up to three quarters). rsin a > 0 (to the right) lowers the left. Both clamp to 0-127, as SsUtKeyOn's voll and volr.

The frames

The first 20 frames (0x80042014, until 0x800c3f24, counted by the flip 0x8001d3e8, reaches 20) read no pads. They slide the text in and draw CANCEL but not ACCEPT. The loop after it (0x80042228) does the pads, the colours, the six labels, the needles' targets, frame start (0x8001d440), the backdrop fade, the backdrop (0x80034fdc, the title's two layers), the heading, CANCEL and ACCEPT (0x80035550, 0x80035674), camera 2 (0x80040010), the meters and needles (0x80042958(0)), the boombox (0x8003f748), the speakers and the arrow blocks (0x8003f934), sounds (0x8006f170), text (0x8002ecd0(1)), the flip (0x8001d3e8(1)) and the controller check (0x80039720). No sign and no babies.

A backdrop fade starts every 30 frames (0x800c4080) as on the title. The loop steps it at its top (0x80042294) and again after the counter (0x800427ec), so while it runs it steps twice a frame. Oracle: the level went 0x80, 0x70, 0x50, 0x30, 0x10, full, where the title goes down 16 a frame.

The text

All spacing 1, white (0xffffff), each over a shadow of 0x010101 drawn first. Positions are from the screen's centre. Strings come through the table at 0x800bb4e8.

Each shadow has the same target as its text, not 2 more. The +0x24 or +0x26 of the three lower items hold the slide's length (164, 143, 63), but no bounce or wobble flag uses them. Seen at rest in the oracle:

• heading (-35, -103), shadow (-33, -103): the wobble leaves both 3 above the target;
• Music (116, -26), shadow (116, -24): 2 below only;
• Sfx (128, 44), shadow (129, 46): the loop slides a shadow only while its text's flag is set (0x80042270 tests the text's +0x18). The Sfx text, 2 pixels nearer, arrives a frame first, so its shadow stops a pixel short with flag 2 still set;
• STEREO (40, 77), shadow (42, 77).

The stereo item's x is 40 at the start whatever the flag, so a menu entered with mono shows MONO at 40 (oracle). A flip sets the string anew and puts the text at (40 for STEREO or 60 for MONO, 75), the shadow at (x + 2, 77), with no flags: the text sits 2 higher than before.

The chosen item is yellow (0x05ffff), the others white (0x80042678); the heading never changes. The loop draws the three shadows, the three items, then after the backdrop the heading's shadow and the heading.

The models

All from database 0 (0x80044b74), drawn with the second camera (0x800e2580, 0x80040010), their matrix from their angles (flag 0x20, 0x80020ee0). Each frame 0x8003f7f0 eases the position (+0x18, +0x1c, +0x20) toward its target (+0xbc, +0xc0, +0xc4) at the speeds (+0xc8, +0xca, +0xcc) and the three angles (+0x24, +0x26, +0x28) toward theirs (+0x2c, +0x2e, +0x30) at +0xce. There is no scale: sizes come from depth.

• The boombox: model 335, 0x800c4b1c, made by 0x80035c1c. (-900, 0, 1000) to (-400, 0, 900), speeds 50, 50, 10 (the z target and speed set at 0x80041ff0); the first angle 0 to 2048 at 150. Drawn by 0x8003f748. Which model is the boombox comes from the screenshot, with its microphone.
• Two meters: model 339 (0x80042b84(0), made by 0x80042958(1)), 0x800c4b30 and 0x800c4b34. (900, -100, 500) to (174, -125, 500) and (900, 100, 500) to (174, 50, 500), speeds 50.
• Two needles: model 340 (0x80042b84(1)), 0x800c4b50 (Music) and 0x800c4b54 (Sfx). (719, -52, 200) to (124, -69, 200) and (719, 93, 200) to (124, 53, 200), speeds 40, 50, 50. The third angle (+0x28, a turn in the screen's plane) starts at 1023. Each frame (0x80042014, 0x80042724) its target is 21 x volume - 1024, clamped to -1024..1024, reached at 128 a frame. 0 points left, about 49 up, 98 and over right. Oracle: 70 gave 446, 85 gave 761.
• The meters and needles are drawn by 0x80042d04, not the usual block draw. It sets the back colour from +0x3a (guess: 0x8009fd18 as SetBackColor) and stores its last argument at 0x800de3d4: 12 for the meters, 0 for the needles (guess: a depth bias that keeps the needles in front).
• Two arrow blocks: model 334 (0x8003f444(0)), sp+0x180 and sp+0x184. (0, 1000, 500) rising to y 220 and to y 150 at 50; angles (1024, 0, 1024) and (1024, 2048, 1024), turn speed 0. The upper one (y 150) shows the up arrow (screenshot).
• Two speakers: model 343 (0x8003f444(3)), 0x800c4b00 and 0x800c4b04, state +0xd2 2. Both at (600, 1800, 4000) rising to y 740 at 150 (z speed 50, turn 128). Their first angle comes from the pair at 0x800c4124: stereo 1536 and 2662, two speakers back to back; mono (the pair at 0x800c4128) 2048 and 2048, one face on. The start always uses the stereo pair, even with mono set (oracle); a flip (0x8004241c) sets the targets from the flag.
• The CANCEL and ACCEPT cubes are the title's: 0x8003ffe8 zeroes their angles at the start and they turn back.

The sounds

Only 1 to 5, through 0x8006f26c (table 0x800b84fc: program, tone, note): 1 (0, 4, 28) cancel, 2 (0, 1, 25) accept, 3 (0, 2, 26) down, 4 (0, 3, 27) up, 5 (0, 13, 37) the effects test.

In the port

rugrats::front::Title runs the loop a frame at a time, sampling the pads at each frame's end as the original does. It has the moves, the shoulder-button sound, the items sliding away before an action (down to 150 at 8 a frame, the second and third waiting 5 and 10 frames), and the countdown. The actions (the Start Game menu, Load Game, Audio) are not ported yet: the port logs them and brings the items back, as if the action had returned nothing. Sounds are recorded by number, not played. Idle or Triangle ends the title, and the program runs the chooser's cycle: a demo movie, the opening, the title again.

The sign, the buttons, the cameras

The front end's camera (0x800e24c0, reset by 0x80040194): field of view 512 (0x8001dfb8: H = 0xa0000 / (rsin(fov/2) << 12 / rcos(fov/2)), kept as 16 bits; 386 here, 178 for the opening's 955), at (0, 30, -500), angles 0. The sign is object 0x800c40a0, model 1038 at the origin. Its state (+0xd0) 1 flies the camera in (z + 600 a frame to -500), 2 out (z - 600 to -17048), 0 holds. Holding, 0x8003f200 nudges the model's vertices every other frame: odd vertices by step k and even ones back by step 4 - k of the five (x, y) steps at 0x800b7dd4, k counting on (0x800c40e8). The steps sum to nothing over five. The trademark (0x8003f0f0) is a raw POLY_FT4, page 0x1e, CLUT 0x64fb, screen (210, -75)-(230, -69), texels (192, 148)-(212, 160), drawn while the sign holds.

CANCEL and ACCEPT (0x80035550, 0x80035674; strings at 0x800bb504, 508) are font-2 text at (-192, -93) and (115, -93) over shadows at +2, +2. Beside each is a cube, a menu block (0x8003f444: model 334 for 0, 332, 342, 343 for 1-3) at (-600 or 600, -400, 1298). It is drawn with the second camera (0x800e2580, 0x80040010: (0, 0, -500), angles 0). Each frame the label's code sets the cube's target angle to 2048 (CANCEL) or 1024 (ACCEPT) at 128 a frame. 0x8003f7f0 eases each angle toward its target and reads a whole turn as none; the loop start (0x8003ffe8) zeroes them, so the cubes turn to show the triangle and the cross. The block's matrix comes from its angles (flag 0x20, 0x80020ee0; checked against the original before its MatrixNormal pass).

The babies (0x80035d44, 0x80043098, 0x80042f34)

Two character objects (0x800c4b20, 0x800c4b24), each holding one of five hierarchy copies (0x800e2440: DB00 hierarchies 1-5). Their parts' quaternions stay zero, which 0x8001fc48 turns into the identity, so they are at rest, turned by their base angles (+0x24; 0x80020d10, the transpose of 0x80020ee0's matrix) and drawn with the second camera at z 4000. Each frame, in the menu's draw: the first's AI (0x80043098), then its move (0x80042f34), then the second's.

The AI, by state (+0x5b2):

• 0: corner = rand() & 7. Below 5, it takes a free corner (re-drawing rand() % 5 while the corner's bit in 0x800c4090 is set) and a free baby (rand() % 5 against 0x800c4094) and marks both. Angles (2176, 64, 512) with targets (2048, 64, z) by corner; speeds 80, 80; turn step 1024. Corners 0-3 start at (+/-3000, +/-2500) and head for (+/-1800, +/-1300) with z turns -1536, 1536, 512, -512. Corners 4-7 go to state 7.
• 1: speeds less 2 a frame; arrived: 2.
• 2: a giggle (0x80070064, two rand calls); back out from the inner point to the outer; speeds 0; 3.
• 3: speeds plus 2 a frame; arrived: 0, the corner and baby freed.
• 4-6: a lean (the y angle to -2304 and back), set from outside.
• 7: sitting out: the corner number counts to 31, then 0. What it marked stays marked.
• 8-9: leaving, set when the menu goes (Start), speeds plus 4 a frame.

The move eases each angle toward its target by the turn step, a whole turn reading as none, and each coordinate by its speed, never past the target.

rand is drawn once before the title's first frame, by an object the front end makes (0x80048a44, the call at 0x80048b78). From there the port's rand and babies match the original's frame by frame (test, 150 frames; 860 compared by hand).

Unknown

• The submenus, the sounds' ids.
• Whether MatrixNormal (0x8009f398) changes the cubes' matrices.